Wide area wireless networks are typically comprised of a cellular radio tower (tower) that is used to communicate with wireless devices over a geographic area referred to as a cell. Many wireless communication specifications employ some form of Time Division Duplexing (TDD) to schedule Down Link (DL) traffic from a tower to one or more wireless devices operating within the cell. TDD is also used to schedule Up Link (UL) traffic from one or more wireless devices within a cell controlled by the tower over common frequency resources.
The Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) specifications provide one example of such specifications that accommodate TDD. An additional specification is the Institute of Electronics and Electrical Engineers (IEEE) 802.16 specification, commonly referred to as WiMax.
To accommodate both DL and UL traffic within the same cell, a TDD configuration can be employed. A TDD configuration provides different time slots for UL and DL transmissions with respect to a common tower. By assigning UL and DL transmission to different time slots, destructive interference, which would otherwise occur if UL and DL transmissions occurred at the same time, can be avoided.
In a wireless network, different towers can experience different demands for DL and UL traffic. For example, there might be a much greater demand for DL traffic at one tower. Whereas, in an adjacent tower, there may be more demand for UL traffic relative to the first tower. To improve efficiency, therefore, it would be desirable to allocate more UL time for the adjacent tower. However, doing so runs the risk of subjecting UL transmissions to interference from more powerful DL transmissions from the original tower near a mobile device.
The interference caused by downlink transmissions is not the only type of interference that can be a problem where nearby towers have asymmetric UL and DL transmission configurations. Another example of a problematic type of interference occurs where one tower is configured to receive UL transmission from wireless devices associated with this tower. However, a nearby tower is configured to provide DL transmission to additional wireless devices associated with this nearby tower. If one or more of the wireless devices receiving DL transmission are sufficiently close to the wireless devices transmitting on the UL, the UL transmissions from the UL wireless devices can interfere with the DL reception of the other wireless devices.
Additionally, to improve spectral efficiency, recent wireless specifications, such as those for LTE, allow for the deployment of Low Power Node (LPN) cellular radio stations within a cell covered by a high power cellular radio tower, which can be referred to as a MaCro Node (MCN). LPNs and MCNs can be part of a heterogeneous network. The interference that can be experienced with respect to these LPNs within the cell of the MCN can be greater than that experienced within an adjacent cell.
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.